Disabling GM’s manual skip shift

GM, in an effort to make their cars slightly more eco friendly, added a feature that puts your car in 4th gear when cruising along in 1st under certain conditions. This is apparently despised by many owners. I is despised so much, that you can buy a commercial product to disable it. That product costs between $20 and $40. Jalopnik has posted a simple solution to disable this feature for under $7 . All you need is a replacement plug and a resistor. It’s really pretty simple.

The orginal “feature” sounds like over engineering a solution on an already flawed system. Why doesn’t GM just address the real issue and replace the whole tranny/engine with one that doesn’t require any skip-shift to pass standards?

my solution on my t56 that has skip shift was not plug the wire in :P. Although I don’t have it in a car that ever came with that engine tranny combo thus idiot lights don’t work. I assume if you just leave things unplugged in a trans am or something that came originally equipped with this it’ll complain at you.

That sounds absurdly dangerous. If you’re driving under these conditions and for some reason need to shift and are expecting to shift into second you’ll be blocked and need to figure out what gear you can move to next? Sounds very bad.

I understand that this would most likely not the case since you would already be in a position to to accelerate if needed. The real point being that you are taking away the natural reaction of the driver and forcing them to do something un-natural. That can have serious consequences.

Blade, please take your idiotic concept of politics elsewhere. The school of “If it ain’t broke, fix it till it is” is not new, nor is it ‘liberal’.

Fitting a workaround like skip shift means not having to scrap thousands of engines and transmissions because they don’t conform to code. In the manufacturer’s accountant’s eyes, it makes sense. Thank goodness for whoever made it so easy to bypass.

It’s called Computer Assisted Gear Selection(CAGS), and it can be easily bypassed with a programmer, no need for any hardware. It was implemented to allow the manufacturer to claim a higher EPA estimated fuel mileage(in town).

if it had never been implemented the only effect would be the lack of nuisance to people who have vehicles with this “feature”. this “solution” has nothing to do with engines, it is implemented in the transmission and the ECM so no engines would have been scrapped. considering the transmission had to be modified to allow this “functionality”, it could have been modified to provide a better solution to the problem; better yet, they could have left the transmission alone and modified the engine to be more efficient.

I understand people being unhappy with a transmission that does this automatically, but it does drastically improve gas mileage to shift to a higher gear at low speeds. The only reason to use the regular sequence of gears is to accelerate. If you’re coasting along in first and you aren’t accelerating, then upshifting to a higher gear lowers engine RPMs and makes the engine use less fuel. Coasting in first with high RPMs is incredibly hard on fuel.

I happen to drive a big Dodge truck with a manual, so this isn’t something automatic or required by my drivetrain, but I do it anyway, as part of trying to get better milage. Driven in an average or typical manner, this truck gets about fourteen highway and eight city, but I can get 28 to 32 highway and 18 city by watching my RPM’s and being careful with coasting and stops.

This isn’t a bug: this is a feature for people who suck at driving manual, which is sadly damn near everyone these days. Overriding this so that you can continue to overrev your engine in first is pretty silly.

Fixes like these (skip shift) hark back to the good old 70s emission quick fixes that rendered otherwise nice cars such a disappointment to drive. Getting basic driveability back usually involved stripping off all the vacuum hoses, rethinking what was really necessary and re-engineering the vacuum system to actually make the vehicle run.

Very few people here seem to understand what skip shift actually is… It does not block 1st gear, it does not make you go from 1-4, it blocks second gear so you naturally go to 4th instead of second by use of a solenoid-actuated shift gate.

Naysayers bug off, skip shift is a brilliant feature that enables Corvettes, CTS-Vs, G8s, etc to exceed the required MPG in EPA tests and avoid the dreaded Gas-Guzzler tax! If you are busy throwing poo at GM over skip shift you should stop and be thankful they made it so damn easy to eliminate this feature which saves owners $1,000s in gas guzzler taxation!

From the Corvette Owner’s manual:

One-to-Four Shift Light
(Manual Transmission)
When this light comes on,
you can only shift from
FIRST (1) to FOURTH (4)
instead of FIRST (1) to
SECOND (2).
You must complete the shift into FOURTH (4) to turn
off this feature. This helps you get the best possible
fuel economy.
After shifting to FOURTH (4), you may downshift to a
lower gear if you prefer.
Notice: Forcing the shift lever into any gear except
FOURTH (4) when the 1 TO 4 SHIFT light comes
on may damage the transmission. Shift only from
FIRST (1) to FOURTH (4) when the light comes on.
This light will come on when:
• The engine coolant temperature is higher than
169°F (76°C),
• you are going 15 to 19 mph (24 to 31 km/h) and
• you are 21 percent throttle or less.

Yeah… I don’t think that the skip-shift is a bad feature… it looks to me like it implements an already understood principle of gear ratio technology in a manner that makes taking advantage of the principles even easier than just looking at the RPM on the dash… you look at a light instead.

The only place I can see people being upset is if they want to shift down for a hill-engine-break or shift up for a drag race.

khordas – it doesn’t work like that. if you’re changing from first to second at low engine load (so long as the engine’s warm) it blocks second so you slide into fourth, thus improving its epa test scores

Who is driving those epa tests? is it some random guy from the street who doesn’t know how to drive economically? if the driver knows how to drive (test driver should), that thing is nothing more than extra weight.

I am once again shocked and amazed at US auto makers that try to “improve” their gas mileage by doing this sort of thing, instead of just building a good engine. I refer you to my Germanride, which gets 30.8mpg (13 liters/100km) running flat-out on the Autobahn, at about 143mph (230 kph). City mileage is about 45ish, depending on the city.

MacGyver:
Those tests are usually “driven” on a test rig. The tires sit on braked rollers, and in front of a ginormous fan. It’s all automated, except for the driver, who has to shit from and to certain gears (if possible) and accellerate so and so hard at this and that time.

I’ll be anal about this. The following was written by Hib Halverson (Technical Writer for Internet & Print Media) who knows more than you.

“The idea that skip shift exists for exhaust emissions (“EPA”) or guzzler tax (CAFE) is urban legend. Skip shift was designed in the mid-80s for the 1989 model year as a way to “beat” the Federal pass-by noise standard. At the time, the test required the driver to start out in first gear, then shift to the next highest gear and go by the microphones at wide open throttle. When GM began development of the 2nd Gen ZR1, it became obvious that, with an exhaust system that allowed the engine to make adequate power, they’d flunk the test, big time. An engineer named Jim Ingle (now retired) came up with the idea of preventing an upshift to second using an electro-mechanical device in the transmission controlled by the ECM which made fourth gear temporarily the next highest gear after first. This forced the driver to go by the microphones during the pass-by test at WOT, low rpm in fourth–and quieter–rather than at high-rpm in second–and louder.

Skip shift has continued, with numerous calibration tweaks, to this day as a hedge against pass-by noise. It is possible that it contributes to fuel economy as well, but I doubt it. EPA mileage ratings are based on a specific drive cycle and I’ve never heard that skip shift contributes to that with any significance.

When you learn the conditions under which the feature enables (some FSMs discuss that), it’s easy to drive around it and there is no performance driving situation–as long as you are properly driving the transmission–where you’ll get skip shift.

The vast majority of drivers who have trouble with it are part-throttle, short-shifting out of first….hardly the way a Vette, a Porsche or any manual trans car should be driven.

You can duplicate the pass-by noise test by starting out in first in a manner that meets skip shifts requirements, then, once you in fourth, go to WOT and accelerate. Have someone stand about 50 back from the road and listen. I guarantee they’ll see, uh….hear the advantage of skip shift. ”

dangerous? the cars it’s in can make it to 50mph in 1st. Plus only complete fools dump more energy into a situation, your BRAKES are far more safe to use. The idiots accelerate to get around something instead of braking to stop.

That said, it’s a dumb thing to add to a stickshift, they should have not cheaped out and put in a crappy tranny.

The Diesel Fuel available in Europe and the Diesel fuel available in America are different. I’m not 100% certain but I’m pretty sure it has to do with sulfur content. Emissions are measured differently between the 2 continents as well, making it very difficult for a diesel engine to pass federal standards. Combine that with the fact that not all filling stations have diesel available, maybe 50% at most, and you see why diesels just aren’t as available in the US.

I would certainly consider some of the excellent diesel cars available in europe, but in the US they kinda suck. Currently a lot of new diesels have a canister of piss that if you don’t replace it, the car won’t start.

The car this is in comes with a 6.0L and gears that reach past or near 200mph, I am sure that your 1.6l is designed to allow your low-torque engine to move off from an uphill stop with reduced drama. (I wish the US was getting the 1.6l focus, or was even getting the 2nd gen focus, we only get a poor old facelift on the 1st gen chassis, while Volvo and Mazda get the 2nd gen chassis, it is stupid.)

@ Jweller:

Actually, they have high tax on Gasoline, no tax on Diesel, high taxes on large petrol cars, tax breaks on Diesel cars etc.

Not to mention the European oil refineries use a method that generates more Diesel fuel, while the method used in the US generates less, thus at a higher cost.

The VW Polo (Lupo?) TDI gets 75mpg and they won’t bring it over here, I blame the poor driving habits of the US and the minimal requirements to pass the license exam.

I was nearly run over several times yesterday, and twice this morning by drivers with no turning signal trying to merge, and traffic not letting me in with my turn signal on.

Also taking my right of way at an intersection, and a car yesterday who performed a left-hand turn nearly into me while I was attempting a right-hand turn on Green.

Not to mention that if you are in the fast lane and want to move to the slow lane you can’t as a couple dozen people are passing you at a 20mph disparity (even though you aren’t the cause of the slow up, but the moron 3 cars ahead who doesn’t understand what a fast lane is for, and is thus going 7mph under the limit.)

The only choice to survive in traffic is to have a car with ridiculous amounts of horsepower, alternating between surges of full throttle and standing on the brakes to make it through between morons completely oblivious to traffic laws.

it seems that the majority of the more intelligent comments here corroborate one thing: people don’t know how to drive *properly* in america. now granted, everyone thinks they’re a great driver – including the soccer-mom in her oversized suv going that (previously stated) 7mph under the speed limit in the fast-lane with the cell-phone glued to her ear (don’t get me started on that tangent!). That being said, we’re back to a situation where manufacturers and government have to step in to reduce the moronic behavior of *most* people. that’s why sites like this are around – we’re not *most* people – we like to take what we have and make it better for *ourselves*, not the masses.

Do I agree with _what_ they’re doing? no. do I agree with _why_ they _have_ to do it? abso-friggin-lutely. society has become so distorted that entities have been forced to idiot-proof everything because the masses don’t want to think for themselves. here’s proof: go get a cup of coffee from mcdonalds and read what’s written in red letters – contents may be hot. think about it – of course the coffee is going to be hot, otherwise you wouldn’t want it. however, some jackass spilled it on herself, sued mcdonalds, and forced them to warn you of the obvious – thereby protecting you from yourself. stupid people make up the masses – it’s a sad fact of life, but it keeps people like me (and many other h-a-d readers i’m sure) employed (and entertained!).

It’s not that there are more stupid drivers in the US than European countries, it’s just that more of the idiots are driving in the first place because the US lacks mass transit outside of major cities (which is 80% of the population).

I am sure you are right about the taxes, and I’m inclined to believe that if there were a greater demand for diesel, refineries would switch methods. I am referring to the fact that until very recently ultra low sulfur Diesel fuel was not available in the US, meaning that it was technically impossible for a European automaker to just bring a diesel car over here. The engine and the emissions system required a redesign to run on our crappy fuel.

Wow. Flame war. At least some people have stayed on the topic and understand that “I want to be able to shift when I feel like it.”, not when the like on the dashboard lights up. Never driven this, but sounds like it does affect a huge number of people. I’m guessing parking lot situations would be the main place this occurs, where it would be natural to be in a first gear creeping along and then hit a more open area where 2nd would be more economical, but finding you can’t pull down into 2nd.

Jweller, Nubie:
Yes, the US has shit diesel, but most Euro cars that I am aware pf tolerate it quite nicely, with the exception being common rail diesels, since the sulfur tends to gunk up the pressure chamber over time. My VW would work fine, the piezo injectors are self-cleaning as long as you use at least “low-sulfur” diesel, and not “straight-from-the-refinery-with-yellow-crystals-floating-in-it” type fuel.

As for the amount of gas stations that carry diesel: Over here, many frequent drivers buy natural gas powered cars, or upgrade their gasoline versions. A Diesel-compatible car is soon to be built by the VW/Audi/Porsche/Skoda/Seat company (using less turbocharging and spark plugs for LNG, a stronger charge and no plugs for Diesel), and people buy those all the time, despite maybe one in six stations actually having the fuel. Maybe we Euro people are just more “green-minded” (which is turning out to be a bad thing, just look at the “no more incandescent bulbs” legislation…), but it seems possible to sell a car that might get rather low on fuel before you can fill up again.

xrayspex – i wouldn’t be surprised if either the writer is wrong or the protocol of the test is flawed. there’s holes in this story, and other more powerful cars have no problems with passing this test. using skip shift if you floor it in first it doesn’t skip to fourth, but enables second to allow you to use the engine’s power, this doesn’t exactly tally with it being to comply with drive by noise restrictions.

whichever version of history is correct is fast becoming immaterial – the system is a lazy hack of one sort or another, and there’s also many lazy hacks in journalism.

I support the traditional definition of “standard”. As as far as mileage goes shift your self to a higher gear like your supposed to. Hope fully no one is retarded enough to try to drive 50 km/h in 1st. It’s that easy folks.

A good majority of posters out here don’t seem to get it. I have an ’04 GTO with the CAGS skip shift enabled. It is more of a nuisance than anything else and I only get affected by it about 2-3 times a year, if that.

First, it only operates if your engine is warmed up and you attempt a manual shift from 1st gear while under 20% throttle. It then moves a small bar up to block the ability to pull the gear selector into 2nd and instead guides it into 4th gear. When you hit 4th there is still plenty of power to continue on and it causes no safety issues. Besides, if you are putting along in 1st and short shift you are probably not looking for a whole lot of power after the shift either.

Also, as soon as it goes into 4th, you can immediately pull it back out of 4th and pull it into 2nd, 3rd or wherever else you like.

The net result: if it is a problem in your car then either apply the fix listed above or don’t buy a HIPO 350+HP car and drive like your grandma. If it is not a feature of your car then why do you even care?

my Z28 had this as well. Yes, it was annoying. I hacked this with a 70-cent resistor. You “Can” just unplug the solenoid plug from the T56 trans, however you instantly get a Check Engine light, because the computer doesn’t see the load of the solenoid coil next time it tries to actuate it. The resistor simply simulates that load, and you happily hit whatever gears you want. I tried to get used to it when I first bought the car, and going from 1 to 4 was just too much (dont forget, 4th gear on the T56 is 1:1 ratio). Around town I usually would go 1,2 and 4, skipping 3rd.